High shot density perforating gun

ABSTRACT

A perforating gun includes a charge tube disposed inside a carrier and a plurality of sets of shaped charges axially distributed along the charge tube and the initiation tube. Each shaped charge of the plurality of shaped charges is supported at an opening in the charge tube. The perforating gun also includes a plurality of detonator cords. Each detonator cord of the plurality of detonator cords connects to one shaped charge in each set of shaped charges.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser. No. 62/213,235, filed Sep. 2, 2015, the entire disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to devices and method for perforating a subterranean formation.

BACKGROUND

Hydrocarbons, such as oil and gas, are produced from cased wellbores intersecting one or more hydrocarbon reservoirs in a formation. These hydrocarbons flow into the wellbore through perforations in the cased wellbore. Perforations are usually made using a perforating gun that is generally comprised of a steel tube “carrier,” a charge tube riding on the inside of the carrier, and with shaped charges positioned in the charge tube. The gun is lowered into the wellbore on electric wireline, slickline, tubing, coiled tubing, or other conveyance device until it is adjacent to the hydrocarbon producing formation. Thereafter, a surface signal actuates a firing head associated with the perforating gun, which then detonates the shaped charges. Projectiles or jets formed by the explosion of the shaped charges penetrate the casing to thereby allow formation fluids to flow through the perforations and into a production string.

In certain instances, it may be desirable to form a relatively large number of perforations within a pay zone. More generally, there may be activities that require a tool capable of providing a high density of perforating jets, such as in connection with well abandonment. The present disclosure addresses the need for perforating guns that can provide high shot density.

SUMMARY

In aspects, the present disclosure provides a perforating gun having high shot density characteristics. The perforating gun may include a carrier; a charge tube disposed inside the carrier; a plurality of sets of shaped charges axially distributed along the charge tube and the initiation tube, each shaped charge of the plurality of shaped charges being supported at an opening in the charge tube; and a plurality of detonator cords, each detonator cord of the plurality of detonator cords connecting to one shaped charge in each set of shaped charges.

It should be understood that certain features of the invention have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will in some cases form the subject of the claims appended thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

For detailed understanding of the present disclosure, references should be made to the following detailed description taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:

FIG. 1 schematically illustrates an end view of a perforating gun according to one embodiment of the present disclosure;

FIG. 2 schematically illustrates a sectional view of the FIG. 1 embodiment;

FIG. 3 schematically illustrates a side view of a prior art perforating gun;

FIG. 4 schematically illustrates an isometric view of a perforating gun according to one embodiment of the present disclosure; and

FIG. 5 schematically illustrates a well completion system that includes a perforating tool according to the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to devices and methods for perforating a formation intersected by a wellbore. The present disclosure is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present disclosure with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein.

Referring now to FIGS. 1 and 2, there is shown one embodiment of a perforating gun 100 in accordance with the present disclosure. The perforating gun 100 may include a carrier 102 that has a bore 103 for receiving a charge tube 104 and an initiation tube 106. The charge tube 104 and the initiation tube 106 each may include openings 108 and 110, respectively, for supporting shaped charges 112. In one embodiment, the carrier 102, the charge tube 104, and the initiation tube 106 may be formed as concentric tubulars made of a suitable material such as metal. However, it should be understood that other configurations, such as strips, may also be used.

As best seen in FIG. 2, the shaped charges 112 may be of convention design and include a case 116 having an open end 118 and a closed end 120. A post 122 may be formed at the closed end 120 and shaped to connect with a detonator cord 124 (FIG. 1). The charge tube opening 108 supports the shaped charge 112 at the open end 118. The open end 118 of the shaped charge 112 may be clipped, screwed, or otherwise fixed within the charge tube opening 108.

The initiation tube opening 110 receives the shaped charge 112 at the closed end 120 and supports the connection between the post 122 and the detonator cord 124 (FIG. 1). In some embodiments, the initiation tube opening 110 is sized to receive the post 122, which may be affixed to the initiation tube 110 using features such as one or more bendable tabs or a charge clip.

In the illustrated embodiment, six sets of shaped charges 112 are axially distributed along the charge tube 104. Each set has five shaped charges 112 circumferentially distributed along a plane 126 transverse to a longitudinal axis 128 of the perforating gun 100 or a component of the perforating gun 100, e.g., the carrier 102. The angular positions of the shaped charges 112 of adjacent sets are phase-shifted. That is, the shaped charges 112 of adjacent sets point radially in different directions. This angular offset allows the space between two shaped charges 112 of one set to be partially occupied by a shaped charge 112 of an adjacent set. Circumferentially offsetting the angular position of the shaped charges 112 in this manner increases the number of shaped charges 112 that can be packed within the internal volume of the perforating gun 100. Of course, greater or fewer sets of shaped charges 112 may be used at each plane 126 depending on the size and configuration of the perforating gun 100. Likewise, a greater or fewer number of shaped charges 112 may be used within each set.

As best seen in FIG. 1, in embodiments, each shaped charge 112 of a given set is independently detonated. For example, each shaped charge 112 of the one set connects to a separate detonator cord 124. In the illustrated embodiment, there are five detonator cords 124 that run in a parallel fashion through an inner bore 130 of the initiation tube 106. Each detonator cord 124 ballistically connects to one shaped charge 112 in each set of shaped charges 112 such that the energy released by the detonator cord 124 is transferred to and detonates the shaped charges 112. The detonator cords 124 may undulate or bend in order to accommodate the phase-shifts of successive shaped charges 112.

In other embodiments, the shaped charges 112 of a given set may be detonated by a common detonator cord 124. More generally, any detonation mechanism that allows the shaped charges 112 to be shifted radially outward and away from the tool axis may be used.

Referring to FIG. 3, conventional shaped charges 20 tend to be arranged closer to a center line or tool axis 22 of a perforating gun 24. Positioning these shaped charges 20 close to the tool axis 22 allows a single detonator cord 26 to detonate all of the shaped charges 20. This positioning reduces the circumferential area along which the shaped charges 20 can be disposed and thereby restricts the total number of shaped charges that can be packed into a given volume of perforating gun.

As shown in FIG. 4, embodiments of the present disclosure position the shaped charges 108 further radially outward from the tool axis 128 (FIG. 2), which increases the amount of circumferential area along which the shaped charges 112 can be distributed and arranged on a transverse plane. Thus, the number of shaped charges 112 that can be packed into a given volume of a perforating gun 100 is increased.

Referring to FIG. 5, there is shown a well construction and/or hydrocarbon production facility 30 positioned over subterranean formations of interest 32. The facility 30 can be a land-based or offshore rig adapted to drill, complete, or service the wellbore 12. The facility 30 can include known equipment and structures such as a platform 40 at the earth's surface 42, a wellhead 44, and casing 46. A work string 48 suspended within the well bore 12 is used to convey tooling into and out of the wellbore 12. The work string 48 can include coiled tubing 50 injected by a coiled tubing injector (not shown). Other work strings can include tubing, drill pipe, wire line, slick line, or any other known conveyance means. The work string 48 can include telemetry lines or other signal/power transmission mediums that establish one-way or two-way telemetric communication from the surface to a tool connected to an end of the work string 48. A suitable telemetry system (not shown) can be known types as mud pulse, electrical signals, acoustic, or other suitable systems. A surface control unit (e.g., a power source and/or firing panel) 54 can be used to monitor and/or operate tooling connected to the work string 48. A perforating gun 100 is coupled to an end of the work string 48. The perforating gun 100 may include one or more detonators 60 that detonate the detonator cords 124 (FIG. 1).

In one mode of use, the perforating gun 100 may be conveyed into the wellbore 12 and positioned at a desired depth. Thereafter, a suitable signal is transmitted to activate the detonator(s) 60, which then fires the perforating gun 100. The projectiles formed by the shaped charges 112 may perform any number of functions including, but not limited to, perforating the formation or a wellbore tubular such as casing or liner. These projectiles may also be used to sever a wellbore tubular so that the tubular may be extracted from the wellbore 12.

The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes. 

What is claimed is:
 1. A perforating gun, comprising: a carrier; a charge tube disposed inside the carrier; a plurality of sets of shaped charges axially distributed along the charge tube and the initiation tube, each shaped charge of the plurality of shaped charges being supported at an opening in the charge tube; and a plurality of detonator cords, each detonator cord of the plurality of detonator cords connecting to one shaped charge in each set of shaped charges.
 2. The perforating gun of claim 1, further comprising an initiation tube disposed inside the charge tube, wherein each shaped charge is further supported at an associated opening in the initiation tube.
 3. The perforating gun of claim 2, wherein the charge tube and the initiation tube are concentric tubular members.
 4. The perforating gun of claim 3, wherein a majority of a casing of each shaped charge is positioned between the initiation tube and the charge tube.
 5. The perforating gun of claim 2, wherein the plurality of detonator cords runs parallel through a bore of the initiation tube.
 6. The perforating gun of claim 2, wherein the plurality of detonator cords runs parallel to a longitudinal axis of the charge tube in a helical manner through the initiation tube.
 7. The perforating gun of claim 1, wherein each shaped charge in at least one set of shaped charges is detonated by a different detonator cord of the plurality of detonator cords.
 8. The perforating gun of claim 1, wherein adjacent sets of shaped charges have an angular phase shift relative to one another.
 9. The perforating gun of claim 1, wherein the shaped charges of each set are circumferentially distributed along a plane transverse to a longitudinal axis of the carrier.
 10. A perforating gun, comprising: a carrier; a charge tube disposed inside the carrier; a plurality of sets of shaped charges axially distributed along the charge tube and the initiation tube, each shaped charge of the plurality of shaped charges being supported at an opening in the charge tube, wherein the shaped charges of each set are circumferentially distributed along a plane transverse to a longitudinal axis of the carrier; a plurality of detonator cords, each detonator cord of the plurality of detonator cords connecting to one shaped charge in each set of shaped charges; and an initiation tube disposed inside the charge tube, wherein each shaped charge is further supported at an associated opening in the initiation tube.
 11. The perforating gun of claim 10, wherein adjacent sets of shaped charges have an angular phase shift relative to one another, and wherein the shaped charges of each set are circumferentially distributed along a plane transverse to a longitudinal axis of the carrier.
 12. The perforating gun of claim 10, wherein the charge tube and the initiation tube are concentric tubular members, wherein a majority of a casing of each shaped charge is positioned between the initiation tube and the charge tube, and wherein the plurality of detonator cords runs parallel through a bore of the initiation tube.
 13. A method of using a perforating gun, comprising: attaching the perforating gun to a conveyance device, the perforating gun including: a carrier, a charge tube disposed inside the carrier, a plurality of sets of shaped charges axially distributed along the charge tube and the initiation tube, each shaped charge of the plurality of shaped charges being supported at an opening in the charge tube, and a plurality of detonator cords, each detonator cord of the plurality of detonator cords connecting to one shaped charge in each set of shaped charges; conveying the perforating gun into a wellbore using the carrier; positioning the perforating gun at a desired depth in the wellbore; and transmitting a signal from a surface location to fire the perforating gun. 